Identification by Inelastic X-Ray scattering of bulk alteration of solid dynamics due to Liquid Wetting

TL;DR

This study uses inelastic X-ray scattering to reveal how a water layer on alumina alters bulk phonon dynamics, causing hardening of acoustic phonons and stress relaxation over hundreds of microns.

Contribution

It demonstrates the impact of liquid wetting on solid phonon behavior and provides a method to probe depth-dependent effects using inelastic X-ray scattering.

Findings

Water wetting causes hardening of acoustic phonons.

Wetting induces relaxation of internal stresses.

Effects are observable up to several hundred microns deep.

Abstract

We examine the influence at room temperature of the deposit of a water layer on the phonon dynamics of a solid. It is shown that the water wetting at the surface of an Alumina monocrystal has deep effects on acoustic phonons, propagating over several hundred microns distance and taking place on a relatively long time scale. The effect of the wetting at the boundary is two-fold: a hardening of both transverse and longitudinal acoustic phonons is observed as well as a relaxation of internal stresses. These acoustic phonon energy changes were observed by inelastic X-ray scattering up to 40 meV energy loss, allowing us to probe the solid at different depths from the surface.